Shift Schedule Optimization For AMT Of Electrical Vehicles Based On Motor Efficiency

Gear change run throughout the whole process of the driving, while shift schedule is in adominant position during the gear change, the automatical shift can be achieved by controltransmission under the control parameters such as specific speed and pedal strength etc,different shift schedules reflect maker’s different demands of dynamic and the economy.Inthis paper, take the motor efficiency of the electric vehicle as constraints and take into accountboth dynamic and economy, to construct a comprehensive evaluation of the performance ofmulti-function that reflect the driver’s intention, in order to optimize the objective, to calculatethe automatic transmission has a multi-performance comprehensive optimal shift schedule，established simulation evaluation system and its simulation evaluation.The main contents of the paper are as follows.(1)The current research status and development trends of electric vehicles, automatictransmission and shift schedule have been introduced briefly, and the aim of this paper is towork out multi-performance comprehensive optimal shift schedule taking into account themotor efficiency, dynamic and economy.(2) Aiming at a certain electric vehicle, transmission system matching is carriedaccording to the performance requirement, the final match of electric vehicle with three-gearautomatic transmission has been achived.(3) According to development methods of traditional shift schedule, the optimizingefficiency shift schedules, optimizing economy shift schedule, optimizing driveability shiftschedules have been respectively established, through the analysis, it’s found that themethod has certain limitation, it only makes shift schedule for single object, but can’t makethe automobile with best comprehensive performance.(4) Based on the analysis of the dynamic performance, economy of vehicle and motorefficiency, evaluation function of shift schedule performance which is in constraint motorefficiency and meanwhile take dynamic performance and economy into account has beenestablished.With the non-dimensional treatment, the comprehensive evaluation function ofmulti-performance comprehensive optimal shift schedule has been proposed. And threedifferent shift schedules under multi-performance constraints for a stepped automatictransmission, which are dynamic performance dominant, economy dominant andcomprehensive optimal of dynamic and economy, are calculated using GA optimizationalgorithm.(5)A simulation-based evaluation system for shift schedule, which consists of motor, thesimulation model of AMT (automated manual transmission), the simulation model of vehiclelongitudinal dynamics, the shift logic simulation model and the simulation model ofECE+EUDC test cycle, have been built using MATLAB/Simulink/Stateflow platform. And the dynamic performance, economy and motor efficiency of six shift schedules of AMT havebeen evaluated through simulation experiments, respectively. The simulation results show that:the shift schedule under multi-performance constraints can achieve good dynamicperformance (regarding dynamic performance dominant shift schedule) or economy(regarding economy dominant shift schedule) of vehicle, meanwhile keeps the economy ordynamic performance at acceptable levels and makes the electric vehicle runnning with higherefficiency, depending on the weights that reflects the driver’s intentions.